BoilerFaultCodes 604 High
Boiler Fault Code 604
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 604 appears across 2 boiler brands and 9 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has stopped working because its internal computer has detected a communication error with the burner control system. (As reported on Worcester Bosch Greenstar 8000 Life/Style)
Pick your boiler brand for the 604 fix
Source
Information for the 604 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026